| Abstract: | Normal guinea-pig serum was found to have a cytotoxic effect in vitro upon several newly induced mouse lymphoblastic leukaemias and on normal mouse thymocytes. This reaction was complement dependent, and cross-absorption experiments showed that the reactivity could be abolished by absorption with any susceptible cell type. It was concluded that normal guinea-pig serum contained a natural antibody which reacted in common with normal mouse thymocytes and certain lymphomas. The growth of lymphomas which had proved highly sensitive to guinea-pig serum in vitro was inhibited by guinea-pig serum in vivo. In contrast, lymphomas showing insensitivity to guinea-pig serum in vitro were also insensitive to it in vivo. It is suggested that the inhibition of lymphoma growth in vivo was due to the natural cytotoxic antibody present in guinea-pig serum. |
